This invention relates to a method of providing the innerside of a neck with a synthetic sleeve, which neck has been formed by the outwardly bent edge of an opening in the wall of a vessel, said sleeve being provided with an internal screw thread for a closure stop.
It is known in such a method to place the synthetic sleeve in a neck and subsequently to shrink the neck radially around the sleeve.
Said known method has several disadvantages. First, due to the shrinkage of the neck the sleeve may obtain an unround shape thereby preventing the closure stop screwed into it from closely engaging the above. Moreover, by deformation of the sleeve internal tensions may occur in the synthetic material which can promote the formation of tensional tears or may lead to shrinkage. Also, the resistance of the the sleeve against rotation inside the neck leaves much to be desired. Finally, it is difficult to seal the sleeve both at the inner side as well as at the outerside of the vessel wtih respect to the neck.
Accordingly, the purpose of the invention is to provide a vessel closure which avoids said disadvantages. (According to the invention this purpose is achieved by use of a sleeve having at one end an outer collar the outer surface of which has the shape of a truncated cone the smallest diameter thereof being disposed at the outer end of the sleeve,) which diameter is smaller than the inner diameter of the neck and of which the largest diameter is larger than the inner diameter of the neck and which at the end turned away from the collar has an outwardly turned flange the distance of which towards the collar is equal to or somewhat smaller than the length of the neck, which sleeve in heated condition is pressed into and through the neck until the collar snaps outwardly over the outer end of the neck.
By mounting the sleeve in heated condition inside the neck permanent deformations and inner tensions do not occur in the synthetic material. This leads to a pure round sleeve and accordingly to a very good sealing of the closure stop. Moreover, due to the absence of internal tensions the sleeve is not susceptible to the occurance of tensional tears or shrinkage.